JPS5924882B2 - Rough rolling method for H-beam steel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rough rolling method for H-beam steel, and in particular is suitable for application to dog-bone rough-shaped steel pieces with a large web height (hereinafter referred to as beam blanks). , open-hole rolling of the beam blank in the pre-finishing universal rolling process
Regarding this.

The manufacturing process for H-beam steel generally involves universal rolling, which involves final forming.Prior to this, it is necessary to roll a beam blank that is fed to this rolling mill.

This rolling is carried out using a breakdown mill having two upper and lower rolls with grooves formed thereon.

However, in the conventional open hole type beam blank breakdown rolling method, due to the geometrical relationship between the hole type and the material to be rolled, the characteristic deformation 6S described in 1 below is generally unavoidable. This is the cause of various inconveniences and restrictions.
It was.

That is, (1) FIG.
Web inner width Wo of 0 (shown by solid line) and hole pattern 2 on the roll
0 (indicated by a broken line) in the web 1w[ has a relationship of wK>Wo.

Therefore, since the flange inner side 11 of the rolled material 10 remains in the hole shape when passing through the roll-by 1, the metal of the flange portion is dragged toward the web surface and the cross-sectional area of the flange is reduced.

(2) The beam blank is rolled in the width direction] The large flange of the plate, and the small web are subjected to uneven rolling in the vertical direction. Some of the metal in the web should flow towards the flange.

However, as the web height increases due to web reduction, the outer surface of the flange of the material to be rolled 10 is reduced to the hole-shaped flange portion outer wall 21.
As the web is strongly pressed, the metal of the flange flows toward the web as the rolls rotate, resulting in a significant reduction in the cross-sectional area of the flange.

(3) As mentioned above, in the rolling of beam blanks, the web reduction ratio > the flange reduction ratio, and these are integrated (
As shown in Fig. 2, there is a large fillet sink 13 and a decrease in flange width 1 as shown in Fig. 2.
Generate 4.

This phenomenon is particularly noticeable in the longitudinal middle part (steady rolling region) of beam blanks for H-section steel with large web heights, and is particularly noticeable in the rolling non-rolling region at the leading and trailing ends. [Stationary region] In this case, it is very slight.

As mentioned above, there is a general tendency for metal to decrease at the flange in conventional breakdown rolling, and in beam blanks made of H-beam steel with a large web height, there is no sinkage at the flange. It was accepted that unevenness in cross-sectional shape at the tip, rear end, and middle part due to the
I had the following problems:

That is, (1) the dimensional accuracy of H-section steel products with a large web height becomes unstable, and the yield rate decreases.

In other words, changes in the amount of shrinkage in the flange portion in the longitudinal direction due to breakdown rolling V directly affect the dimensional accuracy of the product after universal rolling, causing partial tolerance deviations in flange thickness and flange width.

(2) Since the metal in the flange part tends to decrease, when breaking down beam blanks for H-beam steel products with large flange widths or flange thicknesses, the material should be shaped with this in mind in advance. It is necessary to keep it.

Therefore, many types of materials must be prepared depending on the product dimensions, and material integration becomes a significant obstacle to process rationalization.

In particular, continuous casting materials (
The use of beam blanks, blooms, and slabs (beam blanks, blooms, and slabs) is an effective means of reducing costs and improving yields, so many attempts are being made to manufacture a wide variety of products from materials with a single cross-sectional shape. The development of water-rolling technology reduces the number of molds required for continuous casting, and is therefore strongly encouraged from the perspective of saving capital investment costs.

The present invention has been made in order to eliminate the above-mentioned conventional drawbacks, and by suppressing metal loss in the flange portion, it reduces dimensional fluctuations in the rolling direction t and improves dimensional accuracy. Furthermore, it is an object of the present invention to provide a rough rolling method for H-beam steel that can reduce the number of types of materials and integrate the materials by easing the constraint that the cross-sectional shape of the material is determined in accordance with the dimensions of the product. With the goal.

The present invention provides a rough rolling method in which a dog-bone rough-shaped steel piece with a large web height (hereinafter referred to as "beam blank J") is rolled using an open-hole die. (Thickness) Rolling of a beam blank with a diameter of 3.5 or more E At this time, the flange is not constrained by the hole, and only a portion of the web is rolled using a hole that has a protrusion that rolls down only a certain width of the web. By doing so, the above objective is achieved.

The present invention will be explained in detail below.

As a result of a detailed investigation into the deformation of materials during open-hole rolling in a breakdown rolling mill, the inventors have discovered the mechanism by which the cross-sectional area of the plunge portion decreases, which has been a problem in the past. The present invention was made based on this fact.

First, the flange metal reduction mechanism f will be explained.

As mentioned above, there are two types of this phenomenon: one is caused by the restriction of the hole shape, and the other is caused by the difference in rolling reduction between the flange and the web. Taking countermeasures for both is important to improve product dimensional accuracy and improve material quality. This will be crucial in terms of integration.

Reduction due to channel constraint 2 If the inner and outer surfaces 11 and 12 of the flange of the rolled material 10 shown in FIG. It is easy to understand that there is a strong attraction towards

Therefore, it is necessary to take measures to eliminate the constraint of the flange due to the hole shape.
0t, it is sufficient to leave the outer wall 21 of the hole mold 20 open.

Next, the thinning phenomenon of the flange occurs due to the difference in the rolling reduction ratio between the flange and the web.The stretching ratio (length after rolling / Let λT be the length before rolling, and let λF be the respective stretching ratios after rolling (indicated by broken lines) when the flange 15 and web 16 are separated as shown in Fig. 4, then λW
The relationship E holds: 〉λT〉λF.

Therefore, in normal one-piece rolling, a tension force corresponding to λT - λF acts on the flange, so that this portion O≦area is reduced and appears as a sink mark.

This sink mark is seen only in the steady rolling region because the elongation of the web forms a crop and does not strongly act on the flange in the unsteady rolling region at the tip of the material.

Therefore, in order to reduce the thickness sinkage due to the difference in rolling reduction rate, it is necessary to take measures to reduce λT as much as possible.

A factor that affects this λT is web width expansion during web rolling.

In other words, the wider the web width, the smaller the stretching ratio.
The smaller the width spread, the larger the stretching ratio.

FIG. 5 shows the shape of a flat plate (plate width ratio - material width B) during flat plate rolling E.

/Material thickness H8) and the rolling reduction rate on the width spreading rate, and FIG. 6 shows the effects of the plate width ratio and the rolling reduction rate on the stretching ratio l.

From these figures, it can be seen that even at the same rolling reduction ratio, the larger the plate width ratio, the smaller the width expansion, and therefore the larger the drawing ratio.

This situation is the same in the case of web reduction of beam blanks, and when the web part has a large plate width ratio,
λT is larger than that of a small one, and as a result, the phenomenon of thinning of the flange becomes noticeable.

It is a common daily experience that in H-section steels with a large web plate width ratio and a web height of 700mm or more, thinning of the flange in the steady rolling region is likely to occur during breakdown rolling.

It is clear that F) is effective in suppressing the sinking of the E flange by reducing λT.

The present invention has been made based on the above findings.

FIG. 7 shows a first embodiment of the rolling method according to the present invention in which a beam blank with a large web height is used and a beam blank is used.

In this embodiment E, the outer wall 31 of the flange portion is moved sufficiently outwardly so that the groove shape does not restrict the widening of the rolled material 10 that would occur due to web rolling. In both cases, a hole mold 30 is used in which a protrusion 32 is formed so that only a portion of the width B2 at the center of the web is rolled down.

In Figure E, B1 is the width of the web, and Ho is the thickness of the web.

In this embodiment (according to this example, the flange of the material to be rolled 10 is shaped like the hole 3)
Since the flange cross-sectional area is not constrained to 0, a decrease in the flange cross-sectional area is prevented, and only a part of the web with the width B1 and the part with the width B2 are rolled down, and the width ratio of the plate after this rolling is B2.
/Ho, the width expansion is larger at the same rolling reduction ratio than in the conventional method (plate width ratio B1/Ho), and rolling with a small drawing ratio is possible.

The end-rolled part of the web (width B3) in this example is rolled down by the horizontal roll of the open-hole type or rough universal mill, but since the plate width ratio in this case is also small (B3/Ho), the width spread is large. This results in rolling with a small drawing ratio.

FIG. 8 shows the relationship between the open-hole die and the beam blank in the second embodiment of the open-hole rolling method of the present invention.

In this embodiment f, the flange portion outer wall 41 is sufficiently expanded outward, and the hole is formed with a protruding portion 42 that presses down only a width B3 portion at both ends of the web. Type 4
0 should be used.

In this embodiment, first only the web ends are rolled down, and then the central part is rolled down.

The other points are the same as those in the first embodiment, so their explanation will be omitted.

We investigated the relationship between the width of the web section of the beam blank material of various H-shaped steel beam blanks before rolling for breakdown and its width ratio, as well as the relationship between the width of the flange and the variation in plate thickness in the rolling length direction in the final product. However, as shown in Figure 9, it happened.

In this figure, ○ marks indicate small dimensional variations, Δ marks indicate medium variations, and X marks indicate large and problematic variations.

From this, it can be seen that the method of the present invention is effective in preventing dimensional fluctuations caused by sink marks in the flange portion for H-beam steel products in which the plate width ratio of the beam blank web before breakdown rolling is 3.5 or more.

The present invention will be explained in more detail below using specific example E.

Breakdown rolling of an H-section steel with a web height of 900 mm, a flange width of 300 mm, a web thickness of 16 mm, and a flange thickness of 28 mm.At this time, a beam blank material with a web thickness of 120 mm was rolled using the hole pattern shown in Figure 7, and the center of the web was rolled. The approximately 16-width portion was rolled to a thickness of 60 mm, and then the web thickness was made uniform using a conventional slot die, and the product was formed using a universal rolling mill.

The stretching ratio after breakdown rolling was 145 in the conventional method, but was reduced to 1.24 in the method of the present invention, and along with this, the thinning of the flange portion due to tension was significantly reduced.

When the variation (standard deviation) of the flange width 5 and flange thickness measured in the longitudinal direction of the rolling direction was evaluated for products made of the same rolled material, the results were as shown in Table 1 below.

As is clear from this table, the dimensions of the leading and trailing ends of the rolled material and the intermediate part are uniform, and the effects of the present invention are clearly demonstrated.

As explained above, according to the present invention, it is possible to prevent thinning of the flange part in the steady rolling region of the intermediate part in the longitudinal direction of the material to be rolled, and it is possible to supply material having a uniform cross section in the longitudinal direction to the universal rolling mill. .

Therefore, it is possible to roll under stable conditions without losing the balance of rolling between the web and the flange, and products with high dimensional accuracy can be obtained.

In addition, during breakdown rolling, it is possible to control the amount of decrease in the flange metal and the amount of elongation of the web height, so there are fewer restrictions on the shape of the material before breakdown rolling due to the product shape. , it has excellent effects such as being able to manufacture many types of H-beam steel products from one type of material shape.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the relationship between the open hole die and the beam blank before breakdown rolling in the conventional method, Fig. 2 is a sectional view showing the beam blank after breakdown rolling, and Figs. The figure is a diagram for explaining the present invention in detail, and FIG. 7 is a diagram showing the relationship between the open hole die and the beam blank for carrying out the first embodiment of the method for rough rolling H-section steel according to the present invention. FIG. 8 is a cross-sectional view showing the relationship between the aperture type of the funnel and the beam blank, and FIG. It is a line diagram showing a range. 10... Rolled material, 30, 40... Hole shape, 3L41... Flange portion outer wall, 32, 42
...Protrusion.

Claims (1)

[Claims] 1 A rough rolling method in which a dogbone-shaped rough-shaped steel piece with a large web height (hereinafter referred to as "beam blank") is rolled using an open-hole type (thus, the sheet width ratio of the web portion (
When rolling a beam blank with a width (web part width/web plate thickness) of 3.5 or more, a protruding part is formed that rolls down only a constant width part of the web without restricting the flange with a hole shape. A method for rough rolling H-beam steel, characterized in that only a portion of the web is rolled down using a groove.